Prior art concerning such a method of manufacturing the above-mentioned member for electric parts is mentioned in Japanese Patent Laid-open 2000-49195 (Title of Invention: “Process for making a member for electric parts”), in which a method of manufacturing a wireless suspension blank used for HDD is not concretely explained on a method of manufacturing a wireless suspension blank. However, a method of manufacturing a member for electric parts is disclosed as follows.
In the method, a three-layered laminate composed of a polyimide resin film and metallic foils laminated on both sides of the polyimide resin film is used as a laminate. In the process, resist patterns are formed on the metallic foils laminated on both sides of the polyimide, respectively, and the two metallic foils are treated at the same time by etching solution. Thereafter, resist patterns are removed from the two metallic foils, and then plasma etching of the polyimide resin film is made through one metallic foil etched as a mask to form the polyimide resin film into a pattern. Thereafter, the metallic foil used as a mask is removed from the polyimide resin film. As a result, a member for an electronic part can be obtained which is composed of a laminate of the polyimide resin film formed into a pattern and the metallic foil formed into a pattern. This effect is that the low-cost production is possible since reproduction occurs only once and high quality product can be obtained in which a pattern of polyimide resin film is laminated on a pattern of metallic foil with a high positioning accuracy.
However, the above-mentioned process has a first problem in that the three-layered laminate used is high-priced.
Further, the above-mentioned process has a second problem in that working of metallic foil is difficult where finer working accuracy is required, since wet etching is made to the metallic foils laminated on both sides of polyimide resin film of three-layered laminates.
Further, the above-mentioned process has another problem in that flying leads used in checking the action of a magnetic head cannot be formed in a state wherein both sides thereof are exposed to the air.
Further, working of polyimide resin film of the insulating layer is carried out by the dry etching method such as the plasma etching method. However, dry etching has the following basic problem.
FIG. 1 is a schematic illustration of a plasma etching system used for dry etching. The conventional plasma etching system has a flat-plate type of cathode electrode 23, in which cooling pipe 22 is passed. The cathode electrode is secured to a vacuum chamber 21 through RF electrode material 24, and the cathode electrode 23 is connected with power supply 27 through RF introducing pipe 25 and blocking condenser 26. Further, a flat-plate type of anode electrode 28 is arranged parallel with the cathode electrode 23 above the cathode electrode, in which working gas is introduced from the whole surface of the anode electrode 28 and through a gas introducing pipe 29. Further, anode electrode 28 and vacuum chamber 21 are grounded electrically.
In the above-mentioned conventional plasma etching system, dry etching is carried out at a state that a laminate is put on the flat-plate type of cathode electrode 23. In case of polyimide resin film being dry-etched, usually, working of polyimide resin film at high temperature enables higher working speed and high throughput. Therefore, working of polyimide resin film is carried out generally at a temperature in the region of glass transition temperature (Tg) of polyimide resin. However, the laminate of the wireless suspension blank has different metallic materials on both sides. Therefore, if working temperature is in the region of Tg of polyimide resin, curving of the laminate is caused by the very small difference between thermal expansion coefficients of metals so that working efficiency is lowered by local thermal distribution caused by curving of the laminate. Namely, there is a problem that as shown in FIG. 2, a center of the laminate S goes up, in such an extent that the laminate S does not come into contact with cathode electrode 23, and therefore high throughput working becomes impossible.